Colossus is a solid ally for any X-Men hero. Without the resource reduction, he's comparable to War Machine...playable but there might be better options. At the reduced cost, Colossus is a Thor that still triggers your Utopia or Danger Room...fantastic! Colossus is great with Mutant Protectors, making him effectively cost 2 (+himself). Teamwork is also nice to get extra mileage from the 3 ATK despite the high consequential damage. I almost never leave him out of my decks with an X-Men character.